September is one of the warmer months of the year in Phoenix, with average highs near 37.1°C and lows around 22.6°C (mean 29.9°C). It is about average for rainfall, averaging 26 mm of rainfall and 33% relative humidity across the period.
September is one of the warmer months of the year in Phoenix. Across 45 years of records, the warmest September in Phoenix was 2024 — when the month averaged 32.5°C — while the coldest was 1985 at 26°C. Typical September days reach 37.1°C with nights near 22.6°C. The long-term trend is warming, about 0.6°C per decade.
September is about average for rainfall in Phoenix, averaging 26 mm of rainfall. The wettest September on record was 2014 with 94 mm, while the driest was 2000 at 1 mm.
Relative humidity in Phoenix during September averages 33%. The most humid September was 1990 at 47%, and the least humid was 2024 at 20%.
September receives about 6.1 kWh/m²/day of solar energy in Phoenix. The sunniest September was 1993 at 6.6 kWh/m²/day, and the cloudiest was 1997 at 5.6.
Average wind speed in Phoenix during September is 1.9 m/s. The windiest September was 1989 at 2.3 m/s, while the calmest was 2021 at 1.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 28.7°C | 29.5°C | 30.1°C | 30.3°C | 31.2°C | +2.5°C |
| Avg High | 36.1°C | 36.6°C | 37.6°C | 37.3°C | 38.4°C | +2.3°C |
| Avg Low | 21.3°C | 22.4°C | 22.6°C | 23.3°C | 24.0°C | +2.7°C |
| Avg Rain | 35 mm | 28 mm | 17 mm | 27 mm | 23 mm | -12 mm |
September temperatures in Phoenix have risen by about 2.1°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 11°C (1986) to a record high of 45.8°C (2020).
Rainfall in September is about average for rainfall, averaging 26 mm, with a wettest year of 94 mm.
A good time to visit Phoenix
September is a good time to visit Phoenix, with days averaging 37.1°C and nights around 22.6°C (mean 29.9°C, warmer than Phoenix's yearly average) and low rainfall. April and October are marginally more temperate, but September still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 37.5°C | 30.8°C | 24.1°C | 41.6°C | 19.3°C | 50 mm | 37% | 1.8 m/s | 5.7 |
| 2024 🔥 | 40.3°C | 32.5°C | 24.6°C | 45.4°C | 18.2°C | 3 mm | 20% | 2.1 m/s | 6.4 |
| 2023 | 38.1°C | 30.7°C | 23.3°C | 44.6°C | 19.4°C | 20 mm | 27% | 1.8 m/s | 6.1 |
| 2022 | 38.1°C | 31.3°C | 24.5°C | 42.8°C | 20.1°C | 27 mm | 37% | 1.7 m/s | 5.8 |
| 2021 | 36.8°C | 30.1°C | 23.4°C | 42.4°C | 19.0°C | 34 mm | 40% | 1.5 m/s | 5.8 |
| 2020 | 39.6°C | 31.8°C | 24.0°C | 45.8°C | 17.1°C | 2 mm | 21% | 1.9 m/s | 6.3 |
| 2019 | 36.8°C | 30.2°C | 23.7°C | 43.7°C | 17.3°C | 49 mm | 36% | 1.8 m/s | 6.1 |
| 2018 | 39.0°C | 31.9°C | 24.8°C | 42.8°C | 21.8°C | 14 mm | 28% | 1.7 m/s | 6.2 |
| 2017 | 37.0°C | 29.5°C | 22.1°C | 42.9°C | 13.7°C | 4 mm | 26% | 1.9 m/s | 6.3 |
| 2016 | 36.1°C | 29.2°C | 22.3°C | 40.3°C | 14.8°C | 11 mm | 31% | 2 m/s | 5.8 |
| 2015 | 37.2°C | 30.7°C | 24.2°C | 40.4°C | 21.2°C | 20 mm | 39% | 1.7 m/s | 5.7 |
| 2014 🌧️ | 36.1°C | 29.8°C | 23.5°C | 41.5°C | 15.3°C | 94 mm | 44% | 1.7 m/s | 6 |
| 2013 | 36.5°C | 29.5°C | 22.5°C | 43.2°C | 13.9°C | 29 mm | 35% | 1.9 m/s | 6.1 |
| 2012 | 36.6°C | 29.8°C | 23.0°C | 40.9°C | 18.3°C | 22 mm | 36% | 1.8 m/s | 5.9 |
| 2011 | 38.8°C | 31.3°C | 23.7°C | 43.6°C | 19.9°C | 12 mm | 26% | 1.9 m/s | 6.1 |
| 2010 | 39.1°C | 31.1°C | 23.2°C | 43.1°C | 17.6°C | 15 mm | 26% | 1.9 m/s | 6.4 |
| 2009 | 37.5°C | 30.3°C | 23.1°C | 40.5°C | 18.4°C | 21 mm | 29% | 1.9 m/s | 6.3 |
| 2008 | 37.3°C | 30.1°C | 22.9°C | 41.2°C | 19.3°C | 10 mm | 33% | 1.9 m/s | 6.3 |
| 2007 | 37.1°C | 30.1°C | 23.1°C | 42.2°C | 14.6°C | 16 mm | 31% | 2 m/s | 6.2 |
| 2006 | 34.8°C | 27.6°C | 20.3°C | 40.6°C | 13.3°C | 31 mm | 36% | 2 m/s | 6.3 |
| 2005 | 37.8°C | 30.3°C | 22.7°C | 41.0°C | 17.4°C | 7 mm | 25% | 1.9 m/s | 6.3 |
| 2004 | 36.8°C | 29.0°C | 21.3°C | 41.9°C | 13.6°C | 31 mm | 28% | 2.2 m/s | 6.4 |
| 2003 | 38.3°C | 30.8°C | 23.3°C | 42.7°C | 19.5°C | 19 mm | 31% | 1.9 m/s | 6.1 |
| 2002 | 37.4°C | 29.9°C | 22.5°C | 43.0°C | 15.9°C | 31 mm | 33% | 2.1 m/s | 6.1 |
| 2001 | 39.7°C | 31.8°C | 23.8°C | 42.5°C | 19.6°C | 4 mm | 23% | 2.2 m/s | 6.4 |
| 2000 | 39.0°C | 31.1°C | 23.2°C | 44.0°C | 16.9°C | 1 mm | 24% | 2.1 m/s | 6.2 |
| 1999 | 37.3°C | 30.0°C | 22.6°C | 41.3°C | 18.5°C | 34 mm | 36% | 2 m/s | 6.2 |
| 1998 | 37.5°C | 30.2°C | 23.0°C | 41.6°C | 16.9°C | 25 mm | 31% | 2.1 m/s | 6.1 |
| 1997 | 38.0°C | 31.2°C | 24.3°C | 41.8°C | 19.3°C | 23 mm | 37% | 1.9 m/s | 5.6 |
| 1996 | 34.3°C | 27.6°C | 20.9°C | 39.1°C | 13.7°C | 45 mm | 42% | 1.7 m/s | 5.8 |
| 1995 | 37.5°C | 30.5°C | 23.5°C | 42.4°C | 13.9°C | 35 mm | 34% | 1.9 m/s | 6.4 |
| 1994 | 36.9°C | 30.1°C | 23.3°C | 40.7°C | 17.4°C | 32 mm | 36% | 1.7 m/s | 5.7 |
| 1993 | 36.7°C | 28.5°C | 20.3°C | 40.3°C | 14.2°C | 8 mm | 31% | 1.9 m/s | 6.6 |
| 1992 | 37.0°C | 29.4°C | 21.8°C | 40.3°C | 17.4°C | 8 mm | 34% | 1.9 m/s | 6.5 |
| 1991 | 35.9°C | 28.9°C | 22.0°C | 40.0°C | 16.4°C | 21 mm | 36% | 2 m/s | 5.9 |
| 1990 | 35.2°C | 28.6°C | 22.0°C | 41.8°C | 15.2°C | 52 mm | 47% | 1.7 m/s | 5.9 |
| 1989 | 37.8°C | 29.8°C | 21.8°C | 41.3°C | 15.2°C | 9 mm | 24% | 2.3 m/s | 6.3 |
| 1988 | 36.2°C | 28.0°C | 19.7°C | 40.0°C | 14.2°C | 2 mm | 29% | 2.2 m/s | 6.1 |
| 1987 | 36.2°C | 28.6°C | 21.1°C | 40.4°C | 15.6°C | 15 mm | 29% | 2 m/s | 5.9 |
| 1986 | 34.4°C | 26.6°C | 18.8°C | 41.6°C | 11.0°C | 18 mm | 33% | 2 m/s | 5.8 |
| 1985 ❄️ | 33.4°C | 26.0°C | 18.6°C | 39.4°C | 13.8°C | 53 mm | 37% | 2.2 m/s | 5.9 |
| 1984 | 36.5°C | 29.4°C | 22.4°C | 41.1°C | 16.6°C | 75 mm | 43% | 2.2 m/s | 5.8 |
| 1983 | 36.8°C | 30.5°C | 24.2°C | 42.2°C | 17.4°C | 93 mm | 46% | 1.9 m/s | — |
| 1982 | 35.9°C | 28.8°C | 21.7°C | 43.0°C | 13.1°C | 33 mm | 39% | 2.2 m/s | — |
| 1981 | 37.7°C | 30.5°C | 23.2°C | 41.2°C | 17.9°C | 17 mm | 31% | 2 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 37.1°C with lows near 22.6°C (mean 29.9°C), based on 45 years of NASA POWER data.
September averages 26 mm of rainfall in Phoenix, about average for rainfall. The wettest on record was 94 mm in 2014.
The hottest September reached 45.8°C in 2020. The coldest dipped to 11°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.1°C. Daytime highs moved from 36.1°C to 38.2°C and overnight lows from 22°C to 24°C over the same span.
September is one of the warmer months of the year in Phoenix and about average for rainfall, so plan for around 37.1°C daytime highs and 22.6°C at night.
Not quite — September is the 9th coolest month in Phoenix, averaging 29.9°C.
For September in Phoenix, pack light, breathable clothing and sun protection, with typical highs of 37.1°C and lows of 22.6°C.
Relative humidity in September averages 33% — relatively dry.
Average wind speed in September is 1.9 m/s. The windiest September on record averaged 2.3 m/s (1989).
The wettest September on record was 2014 with 94 mm. On average, September sees 26 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Phoenix behaves each September, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for September specifically, along with year-by-year records and how the month has changed over the decades.
